ink

(noun) a liquid used for printing or writing or drawing.

(noun) dark protective fluid ejected into the water by cuttlefish and other cephalopods.

(verb) append one's signature to. Example: "They inked the contract."

(verb) mark, coat, cover, or stain with ink. Example: "He inked his finger."

(verb) fill with ink. Example: "Ink a pen."